Graphene is an attractive material for gas sensing due to its high surface-to-volume ratio and superior carrier mobility. In this study, the effect of mechanical strain on adsorption properties of graphene for NH₃ , CO, H₂O and NO₂ molecules were investigated by first-principles calculations. Our results show that strain can tune the gas binding behavior of graphene, specifically, NO₂ exhibited greater strain sensitivity, with its adsorption energy increasing by 70% under 10% compressive strain. Their I-V characteristics were found to vary as a result of changes in gas molecule adsorption and strain, which were calculated using the non-equilibrium Green's function (NEGF) method. These findings highlight the promising potential of strain-controlled graphene as a continuously tunable sensing material for the development of advanced gas sensors.